1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
6#define UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
7
8#include <algorithm>
9#include <functional>
10#include <string>
11#include <vector>
12
13#include "base/i18n/string_compare.h"
14#include "base/memory/scoped_ptr.h"
15#include "third_party/icu/source/i18n/unicode/coll.h"
16#include "ui/base/ui_export.h"
17
18namespace l10n_util {
19
20// Used by SortStringsUsingMethod. Invokes a method on the objects passed to
21// operator (), comparing the string results using a collator.
22template <class T, class Method>
23class StringMethodComparatorWithCollator
24    : public std::binary_function<const string16&,
25                                  const string16&,
26                                  bool> {
27 public:
28  StringMethodComparatorWithCollator(icu::Collator* collator, Method method)
29      : collator_(collator),
30        method_(method) { }
31
32  // Returns true if lhs preceeds rhs.
33  bool operator() (T* lhs_t, T* rhs_t) {
34    return base::i18n::CompareString16WithCollator(collator_,
35        (lhs_t->*method_)(), (rhs_t->*method_)()) == UCOL_LESS;
36  }
37
38 private:
39  icu::Collator* collator_;
40  Method method_;
41};
42
43// Used by SortStringsUsingMethod. Invokes a method on the objects passed to
44// operator (), comparing the string results using <.
45template <class T, class Method>
46class StringMethodComparator : public std::binary_function<const string16&,
47                                                           const string16&,
48                                                           bool> {
49 public:
50  explicit StringMethodComparator(Method method) : method_(method) { }
51
52  // Returns true if lhs preceeds rhs.
53  bool operator() (T* lhs_t, T* rhs_t) {
54    return (lhs_t->*method_)() < (rhs_t->*method_)();
55  }
56
57 private:
58  Method method_;
59};
60
61// Sorts the objects in |elements| using the method |method|, which must return
62// a string. Sorting is done using a collator, unless a collator can not be
63// found in which case the strings are sorted using the operator <.
64template <class T, class Method>
65void SortStringsUsingMethod(const std::string& locale,
66                            std::vector<T*>* elements,
67                            Method method) {
68  UErrorCode error = U_ZERO_ERROR;
69  icu::Locale loc(locale.c_str());
70  scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
71  if (U_FAILURE(error)) {
72    sort(elements->begin(), elements->end(),
73         StringMethodComparator<T, Method>(method));
74    return;
75  }
76
77  std::sort(elements->begin(), elements->end(),
78      StringMethodComparatorWithCollator<T, Method>(collator.get(), method));
79}
80
81// Compares two elements' string keys and returns true if the first element's
82// string key is less than the second element's string key. The Element must
83// have a method like the follow format to return the string key.
84// const string16& GetStringKey() const;
85// This uses the locale specified in the constructor.
86template <class Element>
87class StringComparator : public std::binary_function<const Element&,
88                                                     const Element&,
89                                                     bool> {
90 public:
91  explicit StringComparator(icu::Collator* collator)
92      : collator_(collator) { }
93
94  // Returns true if lhs precedes rhs.
95  bool operator()(const Element& lhs, const Element& rhs) {
96    const string16& lhs_string_key = lhs.GetStringKey();
97    const string16& rhs_string_key = rhs.GetStringKey();
98
99    return StringComparator<string16>(collator_)(lhs_string_key,
100                                                 rhs_string_key);
101  }
102
103 private:
104  icu::Collator* collator_;
105};
106
107// Specialization of operator() method for string16 version.
108template <> UI_EXPORT
109bool StringComparator<string16>::operator()(const string16& lhs,
110                                            const string16& rhs);
111
112// In place sorting of |elements| of a vector according to the string key of
113// each element in the vector by using collation rules for |locale|.
114// |begin_index| points to the start position of elements in the vector which
115// want to be sorted. |end_index| points to the end position of elements in the
116// vector which want to be sorted
117template <class Element>
118void SortVectorWithStringKey(const std::string& locale,
119                             std::vector<Element>* elements,
120                             unsigned int begin_index,
121                             unsigned int end_index,
122                             bool needs_stable_sort) {
123  DCHECK(begin_index < end_index &&
124         end_index <= static_cast<unsigned int>(elements->size()));
125  UErrorCode error = U_ZERO_ERROR;
126  icu::Locale loc(locale.c_str());
127  scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
128  if (U_FAILURE(error))
129    collator.reset();
130  StringComparator<Element> c(collator.get());
131  if (needs_stable_sort) {
132    stable_sort(elements->begin() + begin_index,
133                elements->begin() + end_index,
134                c);
135  } else {
136    sort(elements->begin() + begin_index, elements->begin() + end_index, c);
137  }
138}
139
140template <class Element>
141void SortVectorWithStringKey(const std::string& locale,
142                             std::vector<Element>* elements,
143                             bool needs_stable_sort) {
144  SortVectorWithStringKey<Element>(locale, elements, 0, elements->size(),
145                                   needs_stable_sort);
146}
147
148}  // namespace l10n_util
149
150#endif  // UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
151